JPH0556758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of operating a clothes dryer that automatically detects dryness and controls exhaust temperature.

2. Description of the Related Art The structure of a conventional clothes dryer of this type is explained with reference to FIG. The material to be dried 3 is rotated and dropped. Reference numeral 4 denotes a motor provided inside the outer box, which rotates the rotary drum 1 via a belt 5 and also rotates an exhaust fan 8 inside a fan case 7 via a belt 6. When the fan 8 is rotated, air passes through the intake port 9 and is heated by the heater 10 to become hot air, which enters the rotating drum 1 and heats the material 3 to be dried to remove moisture. Thereafter, it passes through a filter 11 provided on the rear surface of the rotating drum 1, passes through the fan case 7 and the exhaust port guide 12, and is discharged to the outside of the machine. The object to be dried 3 is dried by the series of operations described above. Reference numeral 13 denotes a temperature sensor installed in the fan case 7 for detecting the temperature of exhaust gas from the drum. As one method for detecting the degree of dryness of the material to be dried, an electrode 14 is attached to the drum support plate 15 via an insulating material 16 such as resin.
Detection is performed based on the resistance value of the dried material 3 in contact with this electrode 14.

The operation in the above configuration will be explained. As shown in FIG. 4, based on the time t until a certain drying rate is reached, which is obtained by utilizing changes in the resistance value between the electrodes 14 or changes in the rate of change in exhaust temperature, etc. The operating time T until the desired drying rate was achieved was set. The temperature inside the drying drum 1 was set to be below a certain temperature Te max in order to protect the material to be dried 3 from high-temperature hot air.

Problems to be Solved by the Invention In such a conventional configuration, the maximum temperature inside the drum 1 is such that when the rated capacity of the material to be dried is placed in the drum 1, the hot air hits continuously and intensively. The temperature has been set at a constant level within the range where the material to be dried is not adversely affected by heat. However, when the volume of the material to be dried 3 is small, even though the hot air does not intensively hit the material to be dried, Temax is constant, so the exhaust temperature is the maximum temperature inside the drum Temax.
As a result, the heat source is stopped for a large amount of time. Therefore, there has been a problem that the operating time required to reach a desired drying rate becomes longer, and as the volume of the material to be dried becomes smaller, the thermal efficiency becomes worse.

The present invention solves these problems,
The purpose of this is to improve thermal efficiency and shorten operating time regardless of changes in capacity without adversely affecting the materials to be dried due to heat.

Means for Solving the Problems In order to achieve the above object, the present invention includes a drum for storing materials to be dried, a temperature sensor for detecting the exhaust temperature from the drum, and a temperature sensor for detecting the temperature of the exhaust gas from the drum. The dryness detection means detects that the dryness rate has been reached, and the control unit controls the energization of the heater so that the temperature detected by the temperature sensor does not exceed an upper limit value, and the dryness detection means keeps the temperature constant from the start of operation. The time it takes to detect the drying rate of the exhaust gas is measured, and the upper limit value of the exhaust temperature is set based on this measured time, and the upper limit value is set lower as the measured time becomes longer.

Effect According to the above configuration, the time from the start of operation until a certain drying rate is detected by the drying detection means is measured, and if the measured time is long, it is determined that the amount of material to be dried is large, and the drum exhaust temperature is On the other hand, if the measured time is short, it is determined that the amount of material to be dried is small, and the upper limit of the drum exhaust temperature is increased. If the amount of material to be dried is small, even if the upper limit is set high, the material will not be damaged by heat, so if the amount is small, the upper limit may be set high to reduce the time required for drying. It is being shortened.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. The basic configuration of the clothes dryer is the same as the conventional one, but the present invention is different in that it includes a control section that changes the maximum temperature inside the drum depending on the amount of items to be dried. The operation of the section will be explained. In the figure, t is the time from the start of operation until a certain degree of dryness is detected, which is determined by a change in the resistance value of the electrode or a rate of change in the exhaust gas temperature. First, by noting that there is a direct proportional relationship between the drying detection time t and the amount of the material to be dried, the amount of the material to be dried can be estimated from the drying detection time t. As shown in Figure 1, the drying detection time t and the maximum temperature inside the drum Temax
Set the relationship to be inversely proportional. Therefore, when there is a large amount of clothing, the dryness detection time becomes long, _t1 .
And based on this t ₁ , the maximum temperature inside the drum is
It is automatically set as low as Temax1. Therefore, as the clothes dry, which is typical when there are a lot of clothes, the clothes swell inside the drum and the hot air is concentrated near the hot air outlet, but as the maximum temperature inside the drum is low, the fabric is not affected by the heat as before. There isn't. Next, when the volume is small, the drying detection time becomes as fast as t ₂ , and the first
From the relationship shown in the figure, the maximum temperature inside the drum is set as high as Temax2. Here, using FIG. 2 and looking at the difference in operating time due to the difference in the maximum internal temperature of the drum, the exhaust gas temperature curve in the case of a small capacity is approximately like B, and increases rapidly after the start of operation. If the maximum temperature inside the drum is set at a constant temperature like Temax2 as in the past, after the rapidly rising exhaust temperature reaches the set temperature Temax2, heat sources such as heaters will stop operating until the temperature drops to the return temperature. However, during this time, it does not contribute to drying the clothes, and as a result, the operation end time becomes longer than _T'2 . However, by setting the maximum temperature inside the drum to Temax1 (higher than the conventional Temax2) based on the drying detection time _t2 , the time period Δt becomes an effective time contributing to drying. Finally, it becomes possible to shorten the operation end time to _T2 .

Effects of the Invention As described above, according to the present invention, the time from the start of operation until a certain drying rate is detected by the drying detection means is measured, and if the measured time is long, it is determined that the amount of material to be dried is large. , the upper limit value of the drum exhaust temperature is lowered, and on the other hand, if the measured time is short, it is judged that the amount of drying material is small, and the upper limit value of the drum exhaust temperature is set high, so the amount of drying material is small. In some cases, the upper limit can be increased and the time required for drying can be shortened.
Further, when the amount of material to be dried is small, even if the upper limit is set high, the drying time can be shortened without being damaged by heat.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram of dryness detection time and maximum temperature inside the drum according to the embodiment of the present invention, Fig. 2 is a characteristic diagram of exhaust temperature, Fig. 3 is a vertical cross-sectional view of a conventional clothes dryer, and Fig.
The figure is a characteristic diagram of conventional operating time, drying rate, and exhaust temperature. 13... Temperature sensor, 14... Electrode.

Claims (1)

[Claims] 1. A drum that stores the material to be dried, a temperature sensor that detects the temperature of the exhaust gas from this drum, a drying detection means that detects that the material to be dried in the drum has reached a certain drying rate, and the temperature sensor. and a control unit that controls energization of the heater so that the detected temperature does not exceed an upper limit value, the control unit measuring the time from the start of operation until the dryness detection means detects a constant drying rate, The upper limit value of the exhaust temperature is set based on this measured time, and the upper limit value is set lower as the measured time becomes longer.